Because of its simple composition and construction, ease of experimental manipulation, regenerative capacity, and stem cell systems, Hydra is a potentially important model system for investigation of a wide range of biological and health-related problems at the tissue, cellular, and molecular levels. The recent completion of the Hydra genome sequence and the publication of a method for making stably transgenic Hydra provide important new tools for exploiting Hydra as a model system. The goal of the project described in this proposal is to generate resources that will allow and motivate the research community to exploit Hydra as an experimental system. To achieve this goal it will be necessary to have a set of vectors with various properties for use in constructing transgenic lines. Thus one of the aims of this project is the development and validation of vectors that will allow: 1. Conditional expression of transgenes;2. Expression of epitope- tagged proteins;3. Loss of function phenotypes by RNA interference and expression of a toxin gene. The second major aim of the project is to carry out high-throughput in situ hybridization to determine the expression patterns of a wide range of genes identified from the Hydra genome project. These will include genes encoding transcription factors, signaling proteins, extracellular matrix proteins, and cell junction proteins. Particular attention will be paid to Hydra genes homologous to human disease genes. The resulting catalog of expression patterns will provide a starting point for functional studies of genes using the transgenic tools developed by the project. Public Health Relevance: Given the currently available tools and resources for Hydra research and the additional resources that we propose to generate, we envision using these resources to exploit Hydra as a model system for basic biological and biomedical research.